This is SCIENCE FRIDAY, I'm Ira Flatow. Earlier this month, New York City's Board of Health approved a first-of-its-kind soda ban that will stop restaurants, movie theaters, street carts from selling sodas and other sugar-filled drinks that are larger than 16 ounces. The soda ban has been controversial among New Yorkers, to say the least. The city's health commissioner says the ban is an important step to fight obesity, which is responsible for the deaths of more than 100,000 Americans and racks up nearly $150 billion in health care costs each year.

But critics say it will only take away personal freedoms and won't be a good way to encourage healthy living. What do you think - a government ban's a good way to curb obesity? What about things like smoking? Is that a different kind of thing? Is that a good precedent?

Give us a call. Our number is 1-800-989-8255, 1-800-989-TALK. You can also tweet us @scifri and go to our website at sciencefriday.com. Brian Wansink is the director of the Cornell Food and Drug Lab at Cornell University in Ithaca. Welcome back to the program.

BRIAN WANSINK: It's great to be on.

FLATOW: Thank you. Marion Nestle is a professor of nutrition, food studies and public health at New York University here in Manhattan. Welcome back, Marion.

MARION NESTLE: Happy to be here. And hi, Brian.

WANSINK: Hello, Marion.

FLATOW: Brian, let's - I know you two have discussed this, so let's get right into this. Brian, you've been a vocal critic of the soda ban. Why are you convinced that it's doomed to fail?

WANSINK: Well, I mean, there's political reasons, but that's not what I deal with. I deal with kind of behavioral reasons, and I really fear that - two things, that this could be a big backfire for public health if it fails; and second, I'm afraid that it will fail because I think when it comes to food and behavior like that, just people don't react and act like we expect them to.

FLATOW: You don't think that it's going to stop people from drinking?

WANSINK: You know, about 150 years of economic research shows that if somebody wants something bad enough, they'll figure a way to get it. And we find all sorts of things sort of have backfired in the past. We did a soda tax study in Utica, New York and we found out that not only did it not really work at curbing the amount of soda people bought, but beer-buying households started buying more beer. If they are taxing soda, well, they just buy beer instead. They wanted something to go with their pizza, and it wasn't going to be tap water.

FLATOW: Marion, let me give you a chance to weigh in. Do you think the government should play a role here?

NESTLE: Oh, absolutely, and the soda ban isn't a ban. It's not a ban. They're not banning sodas. It's a cap on the sizes of sodas that can be offered. And what I love about this conversation is that Brian's own work shows that people eat what's in front of them. If they're given a 16-ounce soda, they'll consume 16 ounces. If they're given 32 ounces, they'll consume 32.

I think this is an idea that's well worth trying because the idea is to try to make the healthier choice the easy choice, and the easy choice is the default - that is, the one you're given. So this isn't a bad idea. Sixteen ounces is two full servings and about 10 percent of daily calories. Anybody who doesn't like a 16-ounce one and wants more can get more. Nobody's stopping them from getting more.

But I think for many people, 16 ounces will be enough because they'll be full, and they won't be hungry and they'll have to ask for another one, which requires effort, and they'll have to pay for one, which is annoying. So I think it may - I think it's got a good chance of working. I'd like to see it tried.

FLATOW: Brian, as someone who does research on why people eat so much in different size bowls and portions - I know we've talked about that before - shouldn't the actual physical size of the cup make a difference?

WANSINK: You know, in studies it makes a tremendous difference because what happens is that if you give someone who typically buys a 12-ounce Coke, for instance, a 32-ounce glass, they are going to drink more. But what happens in the real world is that somebody who wants a 12-ounce Coke buys a 12-ounce Coke. They don't buy a 32-ounce Coke.

So in some ways the huge effects we see in labs can be a little bit artificial because people buy what they want to in the real world, and it's absolutely true that we need to make healthy choices the most easiest, the most convenient choices, but maybe not the only choices. There might have been some other ways to go about doing this.

And one way might have been to encourage fast food restaurants and places like this to give sort of a discount for people, you know, five cent discount on a combo, for people who decided to get a combo meal with Diet Coke instead of full-calorie Pepsi. Trying...

NESTLE: Can I weigh in on that?

FLATOW: Sure, Marion.

NESTLE: I mean - Brian brings up the price issue, which is absolutely critical. I mean, one of the things that soda companies do is they price the larger size at less per ounce than the smaller size. So there's a real disincentive to buy eight-ounce sodas, for example. You can buy eight-ounce cans of soda, but hardly anybody does because you have to pay more for them.

So that's another place where government could intervene, I think, would be to encourage, voluntary, companies to not only serve smaller portions but also price them attractively.

FLATOW: Well, speaking of pricing, let me go to an analogy, or let's talk about cigarette smoking. For years people were told that it was bad to smoke cigarettes, and they had the warning labels and things like that. But people really didn't cut back until they raised the tax on the cigarettes so high, did they? I mean, wasn't that a great incentive? Didn't that cut down on a lot of people smoking?

NESTLE: That and secondhand smoke, which made the social environment such that it became very uncomfortable for people to smoke.

WANSINK: You know, I think - but when we look at that, that's essentially raising the price of something about tenfold. I think what might have become even more important in a case like that was it got banned from restaurants. It got banned from some offices, and it stopped being cool to smoke. And I think those things are probably the bigger social norm drivers of people stopping than the price of cigarettes.

FLATOW: Well, isn't that what the whole purpose of this is?

NESTLE: Yes, exactly, make the social norm something smaller. Good idea.

(LAUGHTER)

FLATOW: Brian, you don't - you seem to be happy with that, that social contract.

(LAUGHTER)

WANSINK: No, I - well, I love these ideas of good, healthy social norms. But I think there's other ways we can kind of encourage them and sort of inspire them, because the thing - if we tell people, look, you are just hopeless, we've got to do things to protect you from yourself, well, I think it's probably the worst public health message we could give people, because we're saying, look, you can't do it yourself, don't even try. That's why we're here.

FLATOW: But we did that with seatbelts, didn't we? People weren't going to buckle up on their own.

WANSINK: Well, seatbelts is one good example. Give me a few more examples.

(LAUGHTER)

NESTLE: Oh, I can think of lots of...

FLATOW: Go ahead.

NESTLE: ...public health measures. I mean these are public health measures, and what public health measures do is to change the environment so people don't have to think about these things, don't even know about them and take them for granted. And many of these public health measures were very, very difficult to introduce when they first started. Everybody made exactly the same kinds of arguments that they're making about the 16-ounce soda cap.

But eventually people got used to it, started taking it for granted. And my guess is that when this starts, people will be shocked at how big a 32-ounce soda is.

I mean, if I had one thing as a public health nutritionist, if I had one thing that I could teach the American public, it would be that larger portions have more calories.

I know it sounds completely ridiculous, but it's not intuitively obvious, as one of Brian's more brilliant experiments showed, that even his trained students don't know that larger portions have more calories, or don't act on it. And so this is a way to make it easier for people to reduce their calorie intake. Good idea.

FLATOW: Let's go to the phones. Mike in Baton Rouge. Mike, go ahead.

MIKE: Yeah, I guess my question is: Is there an incentive for - I don't know if it's the state or city of New York - to be banning these? In other words, if they were taxing it, at least they could take that money and put it towards health care, if that's what they're trying to do. I don't know. Is there any kind of incentive other than just kind of the betterment of society?

NESTLE: Yeah, first of all, it's not a ban. It's a cap, and there's a real difference.

(LAUGHTER)

NESTLE: You can still buy as much soda as you want; nobody's stopping you. I think what happened was that the city health department and Mayor Bloomberg got together and started talking about health problems in New York City and looking at what they could do about them, given the mandates and the laws that they have on the books and what was possible.

And they started dreaming up ideas. And they've come up with one after another after another. And what's really remarkable is at least the first one that they did, which was the trans-fat ban, and that was a ban, is actually working, and there's now research that shows that New Yorkers are eating less trans-fat than they did before the ban went into effect and less than in a lot of other places.

That could have a really important health impact.

FLATOW: We have a tweet, some tweets coming in also, a tweet from TommyThompson(ph), who says: Why is the blame on the drinkers and not the beverage manufacturers? If it is so bad, why won't government have stricter rules on what is in the drinks?

NESTLE: Oh, I'd love to answer that one.

FLATOW: Go ahead.

(LAUGHTER)

NESTLE: It's called lobbying. The soda companies have enormous numbers of firms working for them. They spend tremendous amounts of money lobbying in Congress and exercising their corporate muscle about these kinds of issues. I don't - the idea that this Congress would pass a law that would put restrictions on what soda companies can do just doesn't seem possible to me.

They can't even pass a food safety law that gets through.

FLATOW: We did see a lot of ads here in New York, a lot of counter-ads on TV, and billboards and things like that.

NESTLE: Yeah, those were paid by the American Beverage Association through a grassroots political organization that they invented.

FLATOW: 1-800-989-8255. Let's see if we can get a quick call in before the break. Steve in Pensacola, hi.

STEVE: It's great to talk to you guys, fantastic topic. I just wanted to make a quick point, kind of my personal story. While I was in college, I lost about 100 pounds, and that all started with cutting all sodas out of my diet. And now I just mostly drink water.

But my point is, is that was a personal decision that I had to make. It wasn't something that was enforced by any law that was in place. I think that's where it has to start, with a personal decision.

FLATOW: Would you drink two 16-ounces to get a 32-ounce?

STEVE: Well, actually, Mountain Dew was my beverage of choice, and I actually saw a health report that showed how much sugar was in that, and it really kind of stuck with me, how much was going into my body, how much sugar, which in turn meant calories. So once I saw that, I cut it all out, and I just kind of saw the weight start to melt off.

FLATOW: Interesting, thanks for calling.

WANSINK: That's a great point, Steve.

FLATOW: Yeah, I guess maybe those - you know, that's another thing to do here in New York, is make you put the calories up on the fast food places.

NESTLE: Well, they're already there.

FLATOW: Yeah, they're up. Maybe people like Steve are looking at them and making decisions. We're going to take a break, come back and talk lots more with Brian Wansink of Cornell, Marion Nestle of NYU. Our number, 1-800-989-8255. You can tweet us @scifri. What do you think about sodas, sugar, sweeteners, all kinds of stuff like that and capping them, how many you can get in one glass? Thirty-two ounces doesn't fit in my cup holder. We'll be back after this break. Stay with us.

Let me just scan a few tweets that have come in on the topics from a lot of different ways to look at it. MatthewHarmer(ph) says: If we can cap soda serving sizes, what stops us from limiting food stamp purchases of unhealthy foods, which I would not advocate? Someone else says: 32-ounce soda, JasonDevona(ph) says, is not really 32 ounces of soda because of the ice, right? Does that affect the studies, especially if a customer asks for no ice? People are thinking about it.

(LAUGHTER)

FLATOW: What about subsidizing - if you put a tax on it, subsidizing and maybe giving help out to farmers who grow local, healthy foods?

NESTLE: I love that idea.

FLATOW: Instead of capping it, put a tax on it, and then you can help those farmers markets and stuff make more healthy foods and make them cheaper. Do they think about, Marion, do they think - when they talk about these things, do they think those kinds of options?

NESTLE: Well, it isn't up to Mayor Bloomberg to deal with questions of farm subsidies. That's a federal issue. And the Farm Bill is another one of those pieces of legislation that this Congress can't seem to get passed. So we have a - you know, we have a dysfunctional Congress at the moment, and it's very difficult to deal with these kinds of things at the federal level.

Many of the initiatives in Michelle Obama's Let's Move campaign have been held up for political reasons. (Unintelligible) election's over.

FLATOW: Let's go to Esther in Las Vegas. Hi, Esther.

ESTHER: Yeah, hi, how are you?

FLATOW: Hi there.

ESTHER: Yeah, I just have a quick comment. I just think the whole thing is a bit ridiculous because, you know, if they were really talking, you know, worried about the sugar content, you know, in sodas, et cetera, you know, when is it going to stop? You know, there's, you know, orange juice. If you think orange juice, you know, there's tons of sugar in orange juice. There's a lot of fruit juices that have tons of sugar in it.

And, you know, at what point are they going to draw the line? Are they going to start, you know, taxing us or limiting us on the amount of orange juice we're going to drink or how much sugar we're going to put in our Starbucks coffee? You know, just things like that, just - so I'm just wondering, you know, when they want to draw the line.

And, you know, in addition to that, you know, if a person really wants soda, and they buy one, you know, they're just going to go ahead and buy another one. And, you know, the companies and the movie theaters are just going to make more money. So that's just...

FLATOW: Yeah, you know, if you go - if you go to the movie and you get a smaller drink, you get a free refill with that anyhow, in a lot of theaters.

ESTHER: Yeah, you know, so - you know, if a person really wants their soda, they're going to go ahead and buy another one, and I think it's just more money in the movie theater's pockets, in the - you know, the pockets of the 7-Eleven and all of that. I just think it's just extremely ridiculous. So that's just my comment.

FLATOW: All right, thanks for the call. Brian?

ESTHER: OK, thank you, bye-bye.

WANSINK: Yeah, you bring up some good points, Esther. But one thing that also it suggests is what I'm curious about is if somebody really, really wants that 32 ounces of soda, and they can't get it initially for that discounted rate, so they buy two 16s, if they're a person who can't really afford - if they don't have a lot of money to begin, where's that price of that second soft drink, what does it cut into?

Does it cut into their movie budget, you know, their apple and orange budget? You know, what's it cut into? And I think that would be important to know in some of these cases, what exactly people think and how they make that tradeoff about paying that extra two bucks.

FLATOW: Two bucks? Have you been to the theater lately?

(LAUGHTER)

WANSINK: Oh, yeah.

FLATOW: You know what a 16-ounce soda costs?

WANSINK: I was talking about the $2 they just spent half an hour ago on a Coke.

FLATOW: I see. No, in a theater it's probably four or five bucks for that, for the big soda. But it's a good question. If you had to spend that kind of money and go back and pay for it again, and that's not - you know, theaters is where you pay most for that kind of stuff - would you go back to - if it was not a free refill, would you go back to the counter?

You study the behavior of people who do - who eat a lot, and you have all kinds of experiments with them. What is the most surprising thing about containers and food that affects what people do?

WANSINK: Yeah. Well, one thing, the size of a container does suggest what's normal, what the consumption norm is for situations. So if you give somebody a huge bucket of popcorn, they'll eat most of it, OK. They might not have bought that huge bucket to begin with, but, you know, if you give it to them...

FLATOW: It's there.

WANSINK: Yeah, it suggests how much is normal, appropriate and reasonable to eat, and people just almost dutifully do that. But fortunately, in most restaurants we go into and most movie theaters we go into, there isn't just one big Holy Roman Empire size of bucket. Okay. There's a small, a medium and Holy Roman Empire size.

FLATOW: Would limiting portion size be an effective weight control?

WANSINK: Well, for an individual to do that?

FLATOW: Yeah.

WANSINK: As long as - yeah, as long as what happens is you don't do it too extremely, because once you know that - there's a problem with compensation. And once you know you're really limiting yourself or, you know, cutting out something you kind of want, we have a tendency to try to make up for it later on, you know, eating a bigger dinner because we were a good boy at the movie theater or, you know, ordering extra desserts and things like that.

So as long as it's not too extreme, it works OK, and if we don't even know it's happening, it works even better. That's why things like smaller plates work great for a lot of people.

FLATOW: Let's go to Bob in Brooklyn. Hi, Bob.

BOB: Yes, hi there, very interesting show. I don't really know whether or not the soda law is going to make a giant difference, but what I think would make a giant difference, and I'm sitting here with my wife and son, and they're talking about it as well, would be a law that says any restaurant that you walk into has - any, you know, fast food or in and out, getting falafel or whatever it would be, has to have a spigot for cold water and for seltzer, plain seltzer, or you could have flavored seltzer, but something no calorie, no chemicals, and cups, in a prominent place before you get to the soda spigots.

And if the restaurants objected that they have to give something away, how about 10 cents for the cup for the seltzer, five cents for the cup for the water? But if that's the first thing you see, rather than going sort of around the corner in McDonald's with the soda pump where you can get, you know, your large soda and go over and refill it, perhaps, in some places - I go to Costco. You can get a hot dog and a giant soda. I don't know if they're going to have to change it because it's a wholesale place. You can have all the soda you want and a hot dog for I think it's $1.75 or 2.50. So I think the access of water in a prominent place with a sign as the first opportunity for drinking, that's the law we should...

FLATOW: You know, Bob, years ago in Brooklyn they used to call that a two-cents plain.

BOB: Absolutely.

FLATOW: You have to be old enough to remember that.

BOB: My son is saying also, you know, if you ask for water in a lot of places, they point you to a refrigerator, where you have to buy a bottle of water, and that may discourage people. There's also the illusion that a bottle of water, you're not getting much, but if you buy a soda, you're getting something. You know, it's really all in the shipping anyway, I think, so...

WANSINK: Yeah. Well, Bob, you raise an excellent point.

FLATOW: Thanks, Bob.

WANSINK: And in fact you'll find in a number of fast food places, and I often go to McDonald's, for instance, they'll actually have buttons on the fountain machine where you can - it's a little lever for cold water, and it's a little lever for seltzer water.

But the problem is that it's almost in code. You don't even know it's there unless you eat there way too often. And I think what you say is right: If they made that very obvious, they said, hey, look, here's seltzer water if you push this little button over here...

FLATOW: You can get seltzer water at McDonald's for free?

WANSINK: Yeah, and at Burger King also too. Yeah...

FLATOW: No kidding.

WANSINK: It'll have a little button on the side of either Diet Coke or Coke.

NESTLE: That's a well-kept secret.

FLATOW: That is a well-kept secret.

WANSINK: It is. Just a little bitty lever underneath there. But I think making it obvious like Bob suggested is a great idea.

NESTLE: You have to convince the companies to do it because they're going to lose money on all the soda sales. They're not going to want to do that. I mean, I've talked to restaurant owners and said why don't you give a price break for a smaller portion? And they say, what are you trying to do, put us out of business?

FLATOW: Yeah, because the increase is not proportional to the price.

NESTLE: It's not, no.

WANSINK: But you also raise an excellent point because if they don't start doing something like that, and another place does across the street, they are going to be put out of business because people who want that are going to go to the other place. I think it's a brilliant idea.

FLATOW: What about getting, Marion and Brian, last question, what about getting food companies, food marketing people, to cooperate, you know, in making smaller sizes? You say they're not going to do that?

NESTLE: I think this is the kind of thing that Michelle Obama tried to do with her Let's Move campaign, which is, which has as a big part of it partnerships with food companies to try to work on things that could be done across the board. I think it's difficult.

WANSINK: You know, but there is some nice precedent for this. We had done some work back in the mid-'90s about these - we called them mini-sized portions at that time. And we showed that about 70 percent of all people end up eating less if you give them mini-size portions. That turned into the 100-calorie pack.

FLATOW: And if you give them a tinier plate. If you give them a smaller plate or a bowl, won't they think they're eating a lot?

WANSINK: Yeah, put it in a little thimble, yeah, right.

(LAUGHTER)

FLATOW: We're about out of time. Thank you both. Brian Wansink is director of the Cornell Food and Brand Lab at Cornell University; Marion Nestle, professor of nutrition, food studies and public health at New York University. Thank you both for joining us today. Have a good weekend.

NESTLE: Pleasure to be here.

WANSINK: Have a great weekend. Thank you. Transcript provided by NPR, Copyright NPR.